request.toJSON() not taking into account FormData fields

Currently `request.toJSON()` will only return method, url, data and headers. If there is a POST request with a header `'content-type': 'application/x-www-form-urlencoded;` set along with FormData fields, it will not return them.

It seems to me like a bug. If some data is set and is a part of the request, outputting a JSON representation of that request should not omit such important parts of it.